Prom Dresses
by Nunda
Summary: Derek goes with Casey as she shops for a new Prom dress. DASEY Rated for major adult themes and minor language.


"Prom Dresses"

by Nunda

**Rated** **M** So, if you're squeamish about adult themes turn back now. You have been forewarned. This isn't like my other fics.

Dislaimer: I don't own the show or the characters. Song lyrics belong to Pink from "You Make Me Sick". Also, this is a one-shot involving Dasey.

"Mom, I need the car keys." Casey MacDonald declared, entering the kitchen where Nora was preparing dinner.

"And why do you need the car keys _now? _Dinner will be ready in a minute." Nora replied, stirring some sort of sauce on the stove.

"I need a dress for the prom." She smiled. She was glad she saved all of her babysitting money now.

"The prom? Isn't that for Grades 11 and 12?" Nora questioned.

"Yes." Casey said proudly. "Richie Page asked me out just today."

Derek, who had just came downstairs entered the kitchen and said, "Richie Page is bad news, Case."

Casey whirled around and glared at him. "Just because you couldn't find some senior girl stupid enough to take you to her prom does not mean you can ruin my date."

"Suit yourself." Derek shrugged. "That was just a warning."

"Mom." Casey said. "The keys?"

Nora turned and faced her oldest daughter. "The only way you can go is if you take Derek with you."

"That's not fair." Casey whined. "Why does Derek have to go with me?"

"Yeah, Nora. What'd I do to deserve such punishment?" Derek asked, biting into a piece of garlic bread he'd snuck.

"I know that with Derek with you, you won't be out long." Nora said as she walked to the buffet and picked up her purse. She dug around and pulled out twenty dollars. "This is to get something to eat. And we'll talk about Richie Page later. There will be plenty of stipulations for you to go out with him anywhere."

"Thank you." Derek said and snatched up the bill. "Come on, Case. Let's go."

Casey stuck out her bottom lip. "I'll just go some other time. Like when Emily's home and can go with me."

"No. You're going now." Derek said and grabbed her arm. "Now, come on."

He pulled her with him to the front door.

Casey walked sullenly to the car. Of course her mom would use food as a motivator to make Derek go with her. Derek was motivated by food. Among other things.

Casey slid into the passenger's seat as Derek got in and started the car.

"Where to?" He asked as he backed down the driveway.

"The mall." Casey said.

"Don't you want to eat first?" Derek asked. He could feel his stomach growling.

"We can eat at the mall. _After _I get my dress." She replied.

Absentmindedly, Casey drummed her fingers on the dashboard and stared out her window as they drove toward the mall. Derek put his hand on Casey's to stop her from drumming. She glared at him. He rolled his eyes and turned on the radio.

_You make me sick  
__I want you and I'm hatin' it  
__Got me lit like a candlestick  
__Get too hot when you touch the tip,  
__I'm feelin' it, I gotta getta grip.._

"Oh, I like this song!" Casey said as she grabbed the knob to turn up the volume. Her fingers grazed across Derek's and he quickly jerked his hand away.

He glanced over at her as she began to sing along to the song.

"And it's driving me crazy baby don't you quit. Can't get enough of it. You got me goin' again. Baby, you got me goin' again. You make me sick." Casey sang as she moved her hips back and forth in her seat to the beat.

Derek had to really focus to stay concentrated on the road. It was all too easy to get caught up in watching her plump lips forming the words of the song. And those hips…

"Derek!" Casey yelled, "Don't miss the turn!"

"It's your stupid singing that almost made me miss the turn!" He yelled back as he made a sharp turn to the right and into the mall parking lot.

"My stupid singing?" Casey yelled incredulously.

Derek nodded his head as he looked for a parking spot.

"It wasn't so stupid when I saved D-Rock." She shot back.

"First of all, you didn't save D-Rock--" Derek said as he pulled the car into an empty spot and killed the engine.

"_Casey D-Rock needs you. I'll sign your be nice clause if you just help us out._" Casey mimicked Derek when he all but begged her to join his band.

The cool night air hit them as they got out of the car and walked up to the mall. Casey crossed her arms over her chest as she hugged her jacket closer to her. They walked through the automatic doors and Casey instantly relaxed.

"So, I'll meet you at the food court at…" Casey glanced at her wristwatch. "Eight-thirty?"

"Ouch." Derek said. "Dumping me already? I thought you'd at least let me tag along, ya know…"

"Know what?" Casey interrupted him.

"I could give you a guy's opinion on what dress to choose." He said, offering up his lame excuse. He also wanted to make sure she didn't get a dress that was too revealing. Richie Page didn't deserve that much from Casey.

Casey studied him for a moment. "Fine." She said suddenly and turned and began walking to one of the department stores.

He quickly followed behind her.

Casey grabbed one of each dress on display and took them back to the dressing rooms. She noticed Derek talking to some girl and rolled her eyes. She knew he didn't come with her to give her a guy's opinion on her dress. He just wanted to hit on the other girls who were here buying prom dresses.

Derek heard the click of the door and looked up.

"Listen, Jenny, it was nice to meet you but I've gotta go." He said, his eyes never leaving Casey's dressing room.

He stood by the door and watched as Casey's blue jeans hit the floor. Next, was her shirt. Then he saw her step into a red dress. He listened as she struggled to zip up the back. Hearing the click of the lock, he stepped back. Casey poked her head out.

"There you are." She said to him. "Zip this up for me."

Casey opened the door just enough so Derek could reach in and zip the back for her. He ran his hands down the back of her dress then up again, zipping it closed. Her porcelain skin looked great against the deep red dress.

"Well?" Casey said, stepping back.

Derek took her in. The curve-hugging dress fell just short of reaching her knee caps. The spaghetti straps criss-crossed across her back.

"No." He said. _Richie _definitely_ didn't deserve that dress._

Casey turned and looked in the mirror. "I kind of like it." She said. "I've got a shade of lipstick that matches this dress, too."

"I know." Derek said.

Casey looked up at him questioningly with a cocked eyebrow.

Derek coughed nervously and said, "Try the black one."

Casey shut the door. The red dress hit the floor and Derek saw her step into the black, strapless dress. Just the fact that it was strapless, Derek knew he was going to veto it immediately but that didn't mean he didn't want to see her in it.

When she cracked the door open she was holding the top of the dress up.

"I think I got the wrong size." She said gripping the dress tighter. Her shoulders and neck were so damn tempting.

He pushed her hair back off of her shoulders. "It looks perfect." He said.

"Really?" He could've sworn he saw her blush. "I just have to get a smaller size."

The top of the dress began to slip and Derek caught sight of the curve of her breast before she covered herself up.

_And it's drivin me crazy  
__baby don't you quit…_

"Let me help you with that." Derek said. He reached out and grabbed the top of her dress. His hand brushed over the material covering her pert breast.

"Derek…" Casey said. Her words got caught in her throat as his thumb grazed over her collar bone.

He pushed himself inside the dressing room, closed the door with his foot, never taking his hands off of her. Derek's eyes bore into hers as he leaned down and swiftly kissed her lips.

"_Derek._" Casey said more firmly and pushed him back. "Stop."

She crossed her arms across her chest and his eyes looked at her pleadingly.

"Get out." She demanded. "I have to change and find this in my size."

"I'm sorry Case. You're just so damn beautiful." He finally said. "I'm sorry."

"Stop apologizing and go find this in a size two." She said to him.

He nodded and left the dressing room. What was he thinking? Kissing his stepsister? You've really lost it Venturi, he thought bitterly to himself. He found the rack of black strapless dresses and thumbed through it looking for a size two. He pulled the dress out and held it up. Instantly, he was reminded of her curves.

He knocked lightly on the door and shoved the dress through the tiny crack that she opened the door to.

Derek sat down on one of the benches outside the dressing rooms and waited as she tried on the other dress.

"Derek?" Casey asked as she opened the door again. "I need your help again."

He rolled his eyes again. She was bound and determined to drive him hormonally crazy. Didn't she know what she was doing to him? He was a typical teenage boy, for crying out loud not some asexual freak.

She opened the door allowing him to enter. The door clicked softly behind him. She turned her back to him as she pulled her hair over her shoulder.

"Uh, Case?" Derek said, confused. "Your dress is already zipped."

"I know." Casey said. "I don't need your help _zipping _it. I need your help _unzipping_ it."

"Case—I can't be held responsible for any actions that may occur if I unzip your dress." He said cautiously. Derek was nearly going out of his mind.

"I should hope so." Casey said. "Otherwise you can go back out there and wait on the bench."

Derek shook his head and began sliding the zipper down. Casey closed her eyes and smiled as his hands clumsily ran over her back. He leaned down and kissed her neck.

_I felt my knees get weak...his body was callin' me  
__Just couldn't take the heat…_

"Mmm." She said and turned around to face him. She covered his mouth with her own and meshed her tongue with his. Derek felt himself going hard as Casey pressed her body into his. She lifted her arms up around his neck and the dress slid down to her waist. Derek's eyes fell to her perfect breasts.

He moved his mouth down her neck and to her breasts. His tongue swirled over the dark nipples as he drew them into his mouth.

"Oh…god…" Casey whispered.

They heard voices all around them—shoppers talking and laughing with no idea of what was going on within the four flimsy walls of the dressing room. It added to their excitement. Add in the element of forbidden fruit and Derek was intoxicated.

Casey pushed him into the fold-up chair that was in front of the mirror and finished sliding the dress off of her body. She stood before him in a lacy black thong. She straddled him in the chair and pulled his shirt off. Pressing her skin against his, she pulled his earlobe into her mouth. Derek suppressed a groan and pressed his hardness into Casey.

"Yes." Casey whispered into his ear, answering his unasked question. He grabbed for his belt but her hands took over. She undid his belt and then undid his zipper. Her hands slipped down to his boxers. She massaged the swelling with one hand and ran her hand through his hair with the other. His jeans joined the rest of the clothes—crumpled on the floor.

"My wallet." He whispered. Casey leaned over and grabbed his pants off the floor and pulled out his wallet. She kept rubbing herself against him as he flipped through his wallet and took out a foil package. Casey took it from him and opened it. She rolled it down over his erect cock.

Derek looked up at her, surprised, "So, uptight Casey's not a virgin?"

"There's a lot you don't know about me, Venturi." She grinned.

She slid on top of his member and took him in. Casey bit into his shoulder to keep from moaning and Derek bit down on his bottom lip. Slowly, Casey began rhythmically grinding up and down on him. Derek grabbed a hold of her hips, his nails digging in her skin, as he guided her thrusts. Their mouths connected—tongues frantically fighting each other. Their breathing became more ragged as they began to reach climax. Derek reached down and rubbed Casey's clit, bringing her to orgasm. Casey felt her eyes roll back in her head and her body tense up as she released. Derek reached orgasm next as Casey kept rolling her hips, squeezing his member. Casey relaxed against Derek's chest as their breathing began to return to normal.

"That was…" Casey said.

"Hot." Derek finished. He pulled her closer to him and kissed her lips hard.

There was a pounding on the door and they looked wide-eyed at each other.

"Mall security! Open up in there!" Came an angry voice on the other side.

"Shit." Derek muttered and grabbed his clothes.

"Just a minute." Casey yelled. She frantically looked around for her clothes, shoving her jeans on quickly. Hurriedly, Derek threw his clothes on. Casey pulled her shirt on over her head and threw the door open.

"Can I help you?" She asked as pleasantly as possible. Derek was putting the dresses back on their hangers.

The two security guards staring back at her did not look happy.

"We got a complaint from the manager of noises coming from this dressing room." The tall one said.

"The noises you heard," Derek said standing next to Casey and wrapping an arm around her, "were of my girlfriend here trying on dresses. The zipper got stuck. You need to tell the manager to start inspecting the quality of their merchandise better."

Derek handed the dresses to the shorter guard.

"We need to ask you to leave the store now." The taller one said.

"No problem." Derek said. He moved his arm from Casey's waist to her shoulders as they walked out of the store.

As soon as they were free and clear from the store they both started laughing.

"Do you think they bought it?" Casey asked.

"No." Derek said as he laughed.

"Let's get something to eat and go back home." Casey said.

Derek stopped and looked at her. "What about your dress?" He asked. "There are other stores in the mall that sell prom dresses."

"Oh, I'm not going to prom." She said. "At least not this year. I'll wait and go to my own. With someone else. I mean, Richie Page--he's bad news."

She looked at him and winked.

_And it's drivin me crazy baby don't you quit  
__Can't get enough of it…_

Derek shook his head and followed her to the food court. This girl had him hooked. And he was loving it.

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Review, please! Oh, and I'll be updating TIAL soon. I just had to go ahead and post this.


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